Climate change may quicken with world's oceans absorbing less CO2

A geophysicist from Yale University, US, has found that the world's oceans are absorbing less carbon dioxide (CO2), which could quicken the pace of climate change.

The scientist in question is Jeffrey Park, professor of geology and geophysics and director of the Yale Institute for Biospheric Studies.

He used data collected from atmospheric observing stations in Hawaii, Alaska and Antarctica to study the relationship between fluctuations in global temperatures and the global abundance of atmospheric CO2 on inter annual (one to 10 years) time scales.

A similar study from 20 years ago found a five-month lag between interannual temperature changes and the resulting changes in CO2 levels.

Park has now found that this lag has increased from five to at least 15 months.

"No one had updated the analysis from 20 years ago," Park said. "I expected to find some change in the lag time, but the shift was surprisingly large. This is a big change," he added.

With a longer lag time, atmospheric CO2 can no longer adjust fully to cyclical temperature fluctuations before the next cycle begins, suggesting that the oceans have lost some of their ability to absorb CO2 from the atmosphere.

Weaker CO2 absorption could be caused by a change in ocean circulation or just an overall increase in the surface temperature.

"Think of the oceans like soda. Warm cola holds less fizz," Park said. "The same thing happens as the oceans warm up," he added.

Increases in CO2 levels have tended to precede increases in temperature over the past century, with the human influence on climate accumulating over many decades of burning fossil fuels and clearing forests.

However, this relationship is reversed on inter annual time scales, with multiyear temperature cycles leading multiyear cycles in CO2 levels.